Warren Neale (Roy Stewart), an expert civil engineer, is working on the first transcontinental railroad when he rescues Allie Lee (Marguerite de la Motte) after her family has been killed by an Indian massacre. Through Warren's care, the girl recovers and their friendship ripens into love. Warren leaves Allie at trapper Slingerland's (George Berrell) cabin when he goes to the nearby town of Benton to buy provisions. In his absence, Jose Durade (Robert McKim), claiming that Allie is his daughter, goes to the trapper's cabin, kills Slingerland and abducts the girl. Returning to find Allie gone, Neale, half crazed, searches for her until he collapses in exhaustion and is cared for by "Beauty" Stanton (Kathlyn Williams), the dance hall mistress who loves the engineer. Beauty learns that Durade is holding Allie at his dance hall, rescues the girl and brings her to Neale. Durade, in revenge, gathers his gang together at Beauty's place where in the ensuing battle, both Durade and Beauty are mortally wounded. In her dying moments, Beauty offers the lovers her blessing and they set out together to finish Neale's work on the U.P. Trail.